For some Republicans, the concern about Thursday's vice presidential debate isn't so much what Joe Biden did, or didn't do, to Sarah Palin four years ago, but how he handled a potential Supreme Court justice 25 years ago.

"Biden is the guy who destroyed Robert Bork," one bundler for Mitt Romney told me yesterday. "The guy will be on his A-game, so everyone needs to be aware of that."

(It didn't seem to be the standard expectations-gaming stuff, for what it's worth; the bundler said he was confident in Ryan's ability, too.)

The popular caricature of Biden as a gaffe-prone, beer-swilling, car-washing everyman has some Republicans convinced that Paul Ryan will swamp the vice president with an array of clearly delivered facts and figures, and deliver a debate victory on par with Romney's manhandling of President Obama last week.

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But that doesn't exactly square with the Biden who helped dismantle Ronald Reagan's nomination of Bork in 1987.

As chairman of the Senate Judiciary Committee, it fell to Biden first, and foremost, to match wits with Bork, a highly respected legal scholar who Democrats were hoping to disqualify with a newfound focus on the politics of his legal positions.

Then, as now, not everyone was convinced that Biden was up to the challenge.

''There were three questions,'' Biden conceded at the time. ''Can Biden be fair? Can Biden control himself? And is there any substance there, any depth to Biden?"

The New York Times said he "not only earned praise from all sides for the fairness and good humor with which he ran the proceedings," but also "scored high points on substance in the face of widespread skepticism about whether he had the intellectual depth or the temperament to preside over hearings that promised to turn into a profound constitutional debate."

And he did it all under considerable personal duress.

As Biden presided over the Bork hearings, his presidential campaign was crumbling around him. Accusations that Biden had plagiarized a speech from British Labour Party leader were followed by evidence that Biden had overstated his college and law school performance.

Twice in the course of six days, Biden went straight to the hearing room from tense press conferences dealing with the allegations. After the second one, in which he withdrew from the race, Biden began the hearing by saying: ''Look, my business is behind us. Let's move on.''

On Thursday night, it will be the president's business—a subpar debate performance, followed by dipping poll numbers—that Democrats hope Biden can put behind all of them.

And, though the Romney campaign tries to manage expectations for Ryan, it might be Biden who profits again from being underestimated.

"The expectations of me were so low," he said back then, "that I could have done almost anything except punch Bork and people would have said, 'He's not as bad as I thought.'''